Rhesus monkeys were infected with mutant forms of simian immunodeficiency virus lacking dual combinations of the 4th, 5th, and 6th, sites for N-linked glycosylation in the external envelope glycoprotein of the virus When compared to sera from monkeys infected with the parental virus, sera from monkeys infected with the mutant viruses exhibited markedly increased antibody binding to specific peptides from this region and markedly increased neutralizing activity These results demonstrate a role for N-linked glycosylation in limiting the neutralizing antibody response to SIV and in shielding the virus from immune recognition PUBLICATIONS Reitter, JN, Means, RE, and Desrosiers, RC A role for carbohydrates in immune evasion in AIDS Nature Medicine 1998; 4:679-684